The aim of this proposed study is to investigate the Variable Heavy Chain Pool in the Balb/c mouse immunoglobulins. This will be undertaken by a comparative study of sequences of different heavy chains and a comparison of idiotypic markers in indifferent Balb/c immunoglobulins and myeloma proteins. In particlar, we are comparing the primary structure of phosphorylcholine binding myeloma proteins (TEPC-15, HOPC-8,MOPC l67 and McPC 603) with normally raised antibodies against phosphorylcholine. Comparative studies of normally induced antibodies and 'myeloma' antibodies directed against the same hapten will contribute to our knowledge of the origin of antibody diversity.